<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-08-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001841125</issuerCik>
        <issuerName>Bolt Projects Holdings, Inc.</issuerName>
        <issuerTradingSymbol>BSLK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002028231</rptOwnerCik>
            <rptOwnerName>Naffakh Sami Pascal</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BOLT PROJECTS HOLDINGS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2261 MARKET STREET, SUITE 5447</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94114</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-08-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>750</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2625</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents an award of restricted stock units (&quot;RSUs&quot;). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs will vest in full on the earlier of (1) the date of the Issuer's next annual meeting of stockholders and (2) August 29, 2026.</footnote>
    </footnotes>

    <remarks>On April 21, 2025, the Issuer effected a 1-for-20 reverse stock split (the &quot;Reverse Stock Split&quot;). The share counts herein have been adjusted to reflect the Reverse Stock Split.</remarks>

    <ownerSignature>
        <signatureName>/s/ Paul Joseph Slattery, Attorney-in-fact for Sami Pascal Naffakh</signatureName>
        <signatureDate>2025-12-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
